Establishment of reference CD4+ T cell values for adult Indian population.

BACKGROUND: CD4+ T lymphocyte counts are the most important indicator of disease progression and success of antiretroviral treatment in HIV infection in resource limited settings. The nationwide reference range of CD4+ T lymphocytes was not available in India. This study was conducted to determine reference values of absolute CD4+ T cell counts and percentages for adult Indian population. METHODS: A multicentric study was conducted involving eight sites across the country. A total of 1206 (approximately 150 per/centre) healthy participants were enrolled in the study. The ratio of male (N = 645) to female (N = 561) of 1.14:1. The healthy status of the participants was assessed by a pre-decided questionnaire. At all centers the CD4+ T cell count, percentages and absolute CD3+ T cell count and percentages were estimated using a single platform strategy and lyse no wash technique. The data was analyzed using the Statistical Package for the Social Scientist (SPSS), version 15) and Prism software version 5. RESULTS: The absolute CD4+ T cell counts and percentages in female participants were significantly higher than the values obtained in male participants indicating the true difference in the CD4+ T cell subsets. The reference range for absolute CD4 count for Indian male population was 381-1565 cells/µL and for female population was 447-1846 cells/µL. The reference range for CD4% was 25-49% for male and 27-54% for female population. The reference values for CD3 counts were 776-2785 cells/µL for Indian male population and 826-2997 cells/µL for female population. CONCLUSION: The study used stringent procedures for controlling the technical variation in the CD4 counts across the sites and thus could establish the robust national reference ranges for CD4 counts and percentages. These ranges will be helpful in staging the disease progression and monitoring antiretroviral therapy in HIV infection in India.

Low-cost assays for monitoring HIV infected individuals in resource-limited settings.

Use of a combination of CD4 counts and HIV viral load testing in the management of antiretroviral therapy (ART) provides higher prognostic estimation of the risk of disease progression than does the use of either test alone. The standard methods to monitor HIV infection are flow cytometry based for CD4+ T cell count and molecular assays to quantify plasma viral load of HIV. Commercial assays have been routinely used in developed countries to monitor ART. However, these assays require expensive equipment and reagents, well trained operators, and established laboratory infrastructure. These requirements restrict their use in resource-limited settings where people are most afflicted with the HIV-1 epidemic. With the advent of low-cost and/or low-tech alternatives, the possibility of implementing CD4 count and viral load testing in the management of ART in resource-limited settings is increasing. However, an appropriate validation should have been done before putting them to use for patient testing.

A reliable and inexpensive EasyCD4 assay for monitoring HIV-infected individuals in resource-limited settings.

Serial measurements of absolute CD4+ T-lymphocyte counts are required to initiate and gauge response to therapy and monitor disease progression. Hence, there is an urgent need to evaluate the accuracy and validity of low-cost CD4+ T-cell count assays. Tripotassium EDTA blood specimens from HIV-infected individuals were studied using a novel flow cytometric assay (EasyCD4 assay; Guava Technologies, Hayward, CA) in comparison with standard flow cytometry (FACSCount; Becton Dickinson Immunocytometry Systems, San Jose, CA). The sensitivity, specificity value by EasyCD4 assay in enumerating absolute CD4+ T-cell counts of less than 200 cells/microL were 95% and 100%, respectively. Bland-Altman analysis showed close agreement, with the EasyCD4 assay yielding CD4+ T-cell counts a mean difference of -26 cells/microL (95% confidence interval, -96 to 44 cells/microL) higher than by flow cytometry. Our data suggest that EasyCD4 assay could be a useful alternative assay to conventional flow cytometry, may be appropriate for use in resource-limited settings.